In communications systems, such as a cable communications system, different types of data transfers require different quality of service (QoS), such as delay, bit error rate, and throughput, to transfer data properly to a user's specification. Data transfers within communications systems are typically provided through data streams contained in data packets originating from a number of source communication units (head-end) to a number of destination communication units. Some presently available systems may add integrated services digital network (ISDN) connections to support data traffic in the event of congestion, but these types of connections still carry packetized data from a number of different connections. Other prior art approaches, such as radio frequency (RF) cable modem systems, employ high speed downstream modem technology (e.g., 64 QAM) with simple analog upstream technology (e.g., FSK). This type of system always uses a dedicated circuit-switch connection in the upstream. Such a set up introduces inefficiencies of always remaining in the circuit domain when a packetized connection can be more economical (e.g., in bursty traffic situations). Such a system provides a set upstream traffic capacity and does not address situations in which a greater QoS is required.
Moderate upstream systems also exist. These systems typically employ a shared packet connection. Whereas these moderate speed upstream systems address some of the inefficiencies of always remaining in the circuit domain, they are unable to guarantee a QoS as required by a user. Often times, the QoS data transfer in one direction is inferior (e.g., a lower throughput or a higher bit error rate) to the QoS in the other direction. The result is an unsatisfactory QoS in one direction. Therefore, it would be advantageous to have an improved method and apparatus to efficiently transfer data in a communications system with a high QoS in both directions of data transfer.